So you made it by on $6/hr, which approximates to ~$12.5k/yr before taxes. Under a flat tax that generates the same revenue as today, we'd need about 25% (not counting SS/state sales taxes/state income taxes). Do you think you would have been able to make it with $9,400/yr before state and local taxes and social security? That's $780/month, minus mid 500s in rent, minus $150 car payment leaves $80/month for other utilities, food, health insurance, and enough entertainment to not go insane. Remember, still leaving out state and local taxes.
Even if we assume we magically just need 10%, that leaves you $240/month minus state/local taxes for everything you need, and health insurance would almost certainly eat most or all of that by itself.
That's the better tax plan, in your opinion, than having a wealthier person like you (presumably) are now pick up a somewhat higher, but bearable, burden so that earlier you had a chance to fight his way to your current position? And wealthier people than you are pick up a higher burden so you have a chance to improve your circumstances further, rather than increasing your taxes?
Keeping in mind that in addition to your hard work, you had the previously mentioned luck on your side, and that there's over 50 million Americans making substantially less than you were at the time who would face these same taxes on a flat tax plan without exemption.